1. Field of the Invention
The present invention relates to an image server and an image display system, and more particularly to an image server and an image display system for transmitting a movie picture to a mobile terminal in accordance with the reproducing ability of the mobile terminal.
2. Description of the Related Art
In recent years, along with the development of the third generation mobile phone service (high-speed data communication service), the transmission bandwidth for communication with the mobile phones is enhanced, whereby the rich contents including the movie picture can be distributed to the mobile phones.
However, although the third generation mobile phone service has been practiced, the small-sized mobile terminals such as a mobile phone and a personal information terminal (PDA) are limited in terms of the display size, because a display device such as a liquid crystal display can not be increased in size at the expense of the feature of portability due to its small size.
Though the transmission bandwidth of information is extended and the contents are rich, the mobile terminal is inferior to the personal computer with large screen in terms of its power of expression or the sense of use. An attempt has been made to increase the amount of information for display by setting the resolution, gradation and frame rate of the display device at values as large as possible for the applications of the mobile terminal.
Accordingly, the display devices having different reproducing ability (display ability) are provided depending on the uses of the mobile phone or personal information terminal. In this manner, even when the transmission bandwidth for communication with the mobile phones is increased along with the development of the third generation mobile phone service, it is required to receive and display an image having the number of pixels, gradation, frame rate, compression format, and reproduction bandwidth in accordance with the reproducing ability of the display device provided in the mobile terminal such as mobile phone (because the image having the number of pixels, gradation, frame rate, compression format, and reproduction bandwidth beyond the reproducing ability of the corresponding display device for the mobile phone is not sufficiently reproduced, even if it is received). Also, since the compression formats of image that can be handled by the mobile terminal are not unified, it is required to suitably selectively receive the image.
Conventionally, when the user wants to receive a desired image from an image server accumulating the images via a communication network such as the Internet and display it on the display device of the mobile terminal such as a mobile phone or personal information terminal, it is necessary for the user to examine whether or not the image having the resolution, gradation, or frame rate in accordance with the reproducing ability of the display device for the mobile terminal of the user can be provided in the image server, and selectively receive the image in accordance with the reproducing ability of the display device for the mobile terminal to display it on the display device for the mobile terminal.
In this case, the user needs to select the image adaptable to the display device of the mobile terminal by transmitting or receiving the information to or from the image server, as above described, and this operation is very troublesome for the user.
For example, this procedure is started by the user firstly operating the mobile terminal such as mobile phone to establish a communication connection to the image server via a communication network such as the Internet. Next, a menu page display file for displaying a menu page to download an image is acquired. Then, in the mobile terminal, the menu page is displayed on the display device on the basis of a description of the acquired menu page display file. Next, the user peruses the menu page, and performs an operation of selecting and receiving the image in a compression format reproducible with the type of the user's mobile terminal or its compatible type.
On the other hand, it is required for the service provider providing the image contents to convert the image into the data format conformable to the reproducing ability of the mobile terminal, every time there is an access for image acquisition from various kinds of mobile terminal. An operation of converting the image into the data format to conform to the reproducing ability of the mobile terminal each time (converting the number of pixels, gradation, frame rate, compression format of image) takes a greater amount of computation to increase the amount of processing in the image server, making it delayed to cope with a plurality of users involved in the communication connection. Especially in a case of the movie picture having a great amount of information, there is a significant increase in the computation amount in the image server, imposing a large burden.